Spinocerebellar ataxia type 2-neuronopathy or neuropathy?

Abstract

Introduction: Use of peripheral nerve ultrasound alongside standard electrodiagnostic tests may help to gain insight into the pathophysiology of peripheral nerve involvement in type 2 spinocerebellar ataxia (SCA2).

Methods: Twenty-seven patients with SCA2 underwent ultrasound cross-sectional area (CSA) measurement of median, ulnar, sural and tibial nerves, and motor (median, ulnar, tibial) and sensory (median, ulnar, radial, sural) nerve conduction studies.

Results: Twenty patients had pathologically small-nerve CSAs, suggestive of sensory neuronopathy. In these patients, electrophysiology showed non-length-dependent sensory neuropathy (14 of 20), "possible sensory neuropathy" (1 of 20), or normal findings (5 of 20). Four different patients had length-dependent sensory neuropathy on electrophysiology, and 1 had enlarged nerve CSAs. Regression analysis showed an inverse relationship between ataxia scores and upper limb nerve CSA (P < 0.03).

Discussion: Our findings suggest that a majority of patients with SCA2 (74%) have a sensory neuronopathy and this correlates with disability. A minority of patients have findings consistent with axonal neuropathy (18%). Muscle Nerve, 2019.

Keywords: axonal neuropathy; electrophysiology; nerve ultrasound; sensory neuronopathy; spinocerebellar ataxia.